Migrating Larvae of Sciara Congregata Johannsen

Abstract

The species of Sciara which Prof. Johannsen describes in this issue of PSYCHE, first came under my obser,ation on July 6, 191, when I noticed an army of the larvae in a chain about five feet long and three inches wide at its greatest width. The chain of larva was widest at about the middle and tapered toward each end.The general appearance of the army was that of a dead snake and I was about to pass by it when closer observation showed.that it consisted of a migrating mass of ]arwe. The chain was moving very slowly at a rate of probably not more than a few inches per minute.In general the movement of the army suggested a sort of flowing motion in which the larvm from the rear came up and traveled over their fellows in front of them. It was noticed that the larvm on the top made much better progress than those below. This would naturally be the case since the individuals on the top depended upon those beneath them for purchase. Since the larvae must have been piled up about eight deep in the middle of the procession it would seem that those next to the ground would be unable to make much progress, and that they would therefore have to wait until those to the rear had passed over them before they could gain any headway. It was thus noticed that the advance of the chain was made by the larvm from above. These larvae, naturally, made more rapid progress than those beneath them, and they no sooner gained the ground in front of the chain than they were followed and covered by the great mass of migrating larvm coming from behind. Probably they did not emerge again until most of the chain had passed over them. The locomotion of the individual larva was accomplished by a series of intermittent, jerky, flowing movements by which the larva glided over those beneath it. These migrating larvm left a sort of trail in their wake somewhat similar to the track passed over ly a snake.

Recent discoveries of armyworms in Japan and their species identification using DNA barcoding

“…militaris from Britain (West Scotland) for the first time and made the assumption that soils containing their eggs, larvae, or pupae were transported to the site from northern continental Europe during commercial planting. Armyworms in North America have been identified as Sciara fraterna Say, 1824 in Maryland (Pratt 1899) and as Sciara congregata Johannsen, 1914 in Arkansas (Becker 1914). The cause and function of their impressive mass movements remain unknown.…”

Discovery of snakeworm gnats in Alaska: a new species of Sciara Meigen (Diptera: Sciaridae) based on morphological, molecular, and citizen science data

“…In North America there were two previously-known snakeworm gnat species, Sciara fraterna Say, 1824 ( nomen dubium ), as reported from Poolesville, Maryland by Pratt (1899), and Sciara congregata Johannsen, 1914 (species incertae sedis ), as reported from Arkansas by Becker (1914). Unfortunately, the taxonomic validity of S. fraterna is uncertain ( Steffan 1966; Mohrig et al 2013).…”

“…Sciara congregata is one of two named North American snakeworm gnat species ( Becker 1914). However, we believe it is unlikely that S. congregata is conspecific with S. serpens sp.…”

“…Most sciarid larvae are terrestrial decomposers ( Shin et al 2013). There are reports of sciarid larvae moving in masses while keeping body contact with each other, thus forming conspicuous long columns–over one meter in length ( Becker 1914; Craik et al 2005). This behavior is relatively rare in Diptera.…”

Literature for 1914 on the behavior of spiders and insects other than ants.

“…(3) in the center of infection whole families are attacked simultaneously; (4) in non-pellagrous districts the disease never spreads to others on the advent of pellagrins; (5) in families moving into non-pellagrous districts, children born in the former district are pellagrous, while others are not; (6) the disease is not hereditary; (7) it is not contagious. The advent of pellagra in Kansas gave Hunter (42) an opportunity to conduct a series of experiments which yielded the following results:-"(1) the number of sand-flies is directly proportional to the number of cases of pellagra; (2) the appearance of the cases of pellagra is coincident with the principal broods; (3) just succeeding the time of the principal broods the flies seem to bite more vigorously; (4) sand-flies which have fed on human blood live several days longer than those which have not been so nourished, thus favoring an incubation theory for a parasite, if such there be;…”